1. Field of the Invention
The present invention is related to an imaging apparatus, such as a digital still camera. The present invention is particularly related to an imaging apparatus having a flow shooting function, an image processing method for processing flow shot images, and an image processing program for processing flow shot images.
2. Description of the Related Art
A photography technique called flow shooting is conventionally known. In this technique, photography is performed while panning a camera 1′ to track the movement of a moving object D, such as the car illustrated in FIG. 10A. Thereby, an image P that gives an impression of speed, in which the moving object D (the car) appears to be still while the background T (trees) appears to flow corresponding to the amount of movement of the camera 1′ during exposure, is obtained as illustrated toward the left side of FIG. 10B. However, panning the camera 1′ to track the movement of the moving body D is a difficult photography technique, and many failures occur. In the case of failure, an image P, in which the background T appears to flow but the moving object D is blurred, is obtained as illustrated toward the right side of FIG. 10B.
U.S. Patent Application Publication No. 20060007327 discloses a technique that facilitates flow shooting. In this technique, continuous photography is performed while panning a camera 1′, to obtain a plurality of frame images P1 through P4, as illustrated in FIG. 11A. A reference frame image (frame image P2, for example) is selected from among the plurality of obtained frame images P1 through P4. Positioning processes are administered on the frame images P1, P3, and P4 such that the positions of moving objects D1, D3, and D4 therein match the position of a moving object D2 within the reference frame image P2. Thereafter, the plurality of frame images P1 through P4 are combined, to obtain an image C, in which the moving object D is pictured as a stationary object, even if the movement of the moving object D and the movement of the camera 1′ are slightly shifted.
In the technique disclosed in U.S. Patent Application Publication No. 20060007327, the moving object D is pictured as a stationary object in the ultimately obtained image C. However, in the case that a background T is arrayed from the left side to the right side (the horizontal direction) within images P as in FIG. 11A, and the moving object D moves from the background toward the foreground of the images P of FIG. 11A, that is, in a direction toward the camera 1′, the positioning will result in blurring in the background to foreground direction of the frame images P1 through P4, as illustrated in FIG. 11B. There are cases in which this blurring will result in the flow of the background T becoming discontinuous, as illustrated in FIG. 11A. This discontinuity is due to the panning direction of the camera 1′ and the movement direction of the moving object D not being completely matched. In the case that the background T is discontinuous, the image C appears to flow unnaturally, and the impression of speed may be lost.
In view of this problem, a technique for obtaining the effects of flow shooting has been proposed in Japanese Unexamined Patent Publication No. 2007-074031. In this technique, each of a plurality of frame images P1 through P4 is divided into a moving object D portion and a background T portion. Then, only the moving object portions D are positioned among the plurality of frame images P1 through P4 and combined. A brush process is administered on the background T portions, according to the direction and amount of a difference vector between the movement vector of the moving object D and the movement vector of the background T, to generate an interpolative image. Thereafter, the interpolative image and the combined moving object portion D are combined.
However, there is a possibility that the required processing time and memory capacity will increase, in order to generate the interpolative image in the technique proposed in Japanese Unexamined Patent Publication No. 2007-074031.